This Application is a 371 of PCT/FI97/00545, filed Sep. 9, 1997.
The invention relates to a protective structure, such as a protecting plate or element, that is meant particularly for covering of ground to protect and/or coat the same and/or for a like purpose and, into which there has been arranged at least a thermal insulation and a support arrangement for supporting of the same onto the ground.
For the purpose above, particularly for covering a field of grass or e.g. of ice, it is previously known to use most heterogeneous arrangements. For example covering elements being sold nowadays by the name TERRAPLAS represent particularly more developed solutions, that are made of plastics by injection moulding. To minimize mass of the covering element in question, it has been produced as a perforated structure in a way, that not any actual thermal insulation effect may be achieved by the type of covering element. Correspondingly the support arrangements to support the covering elements against the ground must furthermore be attached to the covering elements by means of totally separate auxiliary devices and work stages. In addition to this locking arrangements connecting the covering elements to each other must be attached separately as well, so that a uniform covering may be achieved by the type of covering elements. The xe2x80x9cperforatedxe2x80x9d structure of the type of covering element above does not either enable exploitation of a so called green house phenomen particularly in connection with a grass field.
The perforated structure of the covering element in question is naturally advantageous with a view to the breathing of the ground, but the perforation causes in addition to those thermal insulation problems such disadvantage as well, that garbage may get collected between the covering and the ground, which naturally eliminates good points of the covering element in question in this respect.
On the other hand it is previously known to use e.g. styrox particularly for covering of ice fields, that has been surrounded by both sides of the same by plywood plate. This type of solution is naturally not applicable as such to be installed particularly on a grass field, in case not totally separate foot structures are being used to raise the covering structure apart from the ground. On the other hand when being used in connection with an ice field, such problem of this type of solution has been found, that the plywood plates tend to freeze to the ice, that is why loosening of the same is laborious. In addition to that the type of constructions are very heavy, that is why storing as well as use of the same in actual coating is disproportionately difficult.
On the other hand application document DE 41 12 757 discloses a covering element, in which there has been arranged a supporting arrangement, that comprises a platform structure under the same to achieve e.g. an air space between the covering element and the ground under the same. In this solution the actual platform structure has been formed, however, from a separate material layer, that has been attached fixedly e.g. by means of a glue layer to the actual frame structure, to the opposite surface of which there has been attached e.g. by a glue layer a surface layer. In the solution in question there has been exploited furthermore rubber based material, that is why not any particular thermal isolation effect may be achieved with the covering element in question. Because production of the solution in question requires several work stages, this type of covering elements get disproportionately expensive. Furthermore in patent U.S. Pat. No. 4,291,851 there has been represented a structure solution, that is not meant particularly as a covering element to be applicable for temporary protecting of ground, but instead as a uniform and constant internal casing of an aeroplane, that is why it is not in any way obvious to exploit the construction in question of the same for the purpose described herewith. Furthermore in patent U.S. Pat. No. 3,870,587 there has been shown differing panels, the constructions of which are very traditional and which are applicable e.g. for covering of ice field, but the compositions of which correspond mainly the prior art technics described in the beginning, that is why they are particularly expensive to produce. This is why they do not have either any kind of price competition ability, when keeping in mind modern demands.
It is the aim of the protective structure according to this invention to achieve a decisive improvement in the problems presented above and thus to raise substantially the level of knowledge in the field. To achieve this aim, the protective structure according to the invention is primarily characterized in, that the thermal insulation of a protective structure, that is meant particularly for temporary protecting of a field of grass and/or of ice comprises at least one, preferably plastic based, such as cell, cellular, foam plastic structured or a like thermal insulation layer, whereby a support arrangement, that is formed of the bottom surface of the same, comprises a platform structure projecting from the basic wall thickness of the thermal insulation layer, particularly to achieve an air space between the protective structure and the ground under the same.
As the most important advantages of the protective structure according to the invention may be mentioned simplicity and technical workability of the construction, production and use of the same. The structure according to the invention enables first of all a very good thermal insulation ability thanks to that, that in addition to the thermal insulation layer this influence is being effected by means of the air space between the protective structure and the ground. Furthermore the feet being arranged as a built-in platform structure directly to the bottom surface of the thermal insulation layer prevent first of all xe2x80x9cburningxe2x80x9d of the grass that is left under the protective structure, and on the other hand freezing of the type of protective structure in question onto the ice. The protective structure according to the invention is furthermore significantly lighter than the corresponding nowadays solutions, that is why it is idealistic both with a view to use, installation as well as storing. The protective structure according to the invention does not require either support arrangements to be attached to the same by separate work stages or other stiffening structures, but instead all the above may be produced totally built-in during production of the protective structure. The protective structure according to the invention is, as explained above, advantageous in that respect as well, that alike construction may be exploited in principle both for covering of fields of ice as well as of grass.
Advantageous embodiments of the protective structure according to the invention are represented in the dependent claims related to the same.